The present invention relates to tire molds. More particularly, it relates to the molding of the markings provided on the sidewalls of the tires.
It is well known that the sidewalls of tires bear a large number of markings: the name of the manufacturer, the type of tire, its size, as well as the markings required by the regulations concerning the plant of manufacture, the date of manufacture, and the loading or speed capacity of the tire, and even other markings. These markings are produced by providing the negatives corresponding to these markings on the mold. The part of the mold which assures the molding of the outer surface of the sidewall of a tire is known as the shell. It comprises letters machined in the mass as well as removable plates used for the markings which contain indications which must be regularly changed, such as, for instance, the period of manufacture of the tire. An example of such a removable plate is given in U.S. Pat. No. 4,547,139.
At the present time efforts are being particularly directed to the presentation of those markings of an advertising nature. For instance, purely decorative motifs are added on the sidewall of the tire in order to create in the mind of the consumer a means of identifying the unit of a range of products of a manufacturer. The name of the manufacturer and the type of tire must appear on the sidewall of the tire in as attractive a manner as possible. This leads the designers of tires to provide markings in relief or recessed with reference to the surface of the sidewall of the tire and/or to produce on the marks striations intended to make the letters stand out with respect to the sidewall of the tire. It is desirable to leave as great as possible a latitude for the design of the markings with respect to their shape and appearance. Furthermore, it is desirable that the quality of the molding remain perfect, that is to say that no molding defect appears, such as, for instance a lack of rubber in certain regions of the markings, due to air pockets in the mold.